Bicycles have been and still are one of the more popular forms of sports and transportation equipment. The chain drive means in a bicycle is used to transmit the power placed on the driving sprocket by the user to the driven wheel of the bicycle which generally is the rear wheel. In many instances, the driven wheel is provided with a plurality of different sized gears so that the user may use a shift mechanism so as to rotate the driven wheel at different speeds and is commonly referred to as a derailer system such as that described in U.S. Pat. No. 4,343,613 to Leiter et al. It is very essential that the chain drive means used on bicycles equipped with a derailer system be kept clean from deleterious materials which would prevent the proper operation of the chain drive means. This is particular true when the bicycle is operated in rough terrain or when the bicycle is used in jumping operations that result in a force being applied to the lower run of the chain system. In many instances, the weight of the chain and the force applied thereto will be more than enough to overcome the tension applying means of the derailer system so that the lower run of the chain will strike the terrain and have deleterious materials attached thereto.